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Bicuspid aortic valve in competitive athletes
  1. L Stefani1,
  2. G Galanti1,
  3. L Toncelli1,
  4. P Manetti1,
  5. M C Vono, MD1,
  6. M Rizzo1,
  7. N Maffulli2
  1. 1
    Sport Medicine Center, University of Florence, Florence, Italy
  2. 2
    Keele University School of Medicine, Keele, UK
  1. Dr L Stefani, Viale Gian Battista Morgagni, 85, 50134 Florence, Italy; laura-stefani{at}tiscali.it

Abstract

Aim: Bicuspid aortic valve (BAV) is a common congenital cardiac condition. The presence of BAV in non-elite athletes has been poorly investigated; it is usually asymptomatic until valvular stenosis, regurgitation or other vascular alterations are evident.

Design: Over a three-year period, 2273 competitive athletes were consecutively investigated with transthoracic echocardiography. The traditional parameters, the aortic root dimensions at four levels and the systolic and diastolic flow of aortic valve, were studied with continuous Doppler according to the echo guidelines.

Setting: The study protocol included all the non-elite athletes investigated for the first evaluation to obtain eligibility.

Patients: 2273 competitive athletes aged 8–60 years from several sports and regularly trained were evaluated with anamnesis, clinical check-up and echocardiography in order to exclude subjects with systemic or congenital heart disease.

Results: BAV was diagnosed in 58 athletes (2.5%). Of these, nine had normal valvular function, 47 had abnormal valvular function with mild–moderate aortic regurgitation, and two had moderate stenosis. Aortic root dimensions at all levels were significantly greater in athletes with BAV than in athletes with a normal tricuspid valve. No relation was found with age, body surface area, aortic regurgitation or years of training.

Conclusions: BAV is a relatively common congenital cardiac disease in athletes and commonly asymptomatic for a long time. This study suggests the usefulness of evaluating young athletes using echocardiography at least once when they start their sporting activity.

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Bicuspid aortic valve (BAV) is the most common congenital cardiac condition, occurring in 1% to 2% of the general population.1 2 It is often associated with other vessel abnormalities and anomalies of the left ventricular outflow tract.3 However the prevalence, while known in the young population in general4 and in elite athletes,3 is still mostly unknown in non-elite but competitive athletes.5

Most people regularly practise sport, and BAV does not normally represent an obstacle to eligibility, even if the impact that regular training can have on an athlete’s heart with BAV has not yet been clarified.3 4 11 12 We thus surmise that early identification of subjects with BAV might help in following up the modifications and perhaps preventing the associated adverse consequences of training.610 This is particularly important if we consider that the clinical symptoms of BAV are evident only after 40 years of age.3 4 11 12 In this context, echocardiography could be considered a sensitive and reliable tool for detecting aortic lesions13 and congenital cardiac conditions, and has in fact recently been used to detect the true prevalence of BAV in newborns.14

In most western countries, the pre-participation screening (PPS) protocol currently used includes personal and family history and physical examination with cardiac auscultation. All these enable the clinician to suspect the presence of BAV, but not to formulate a definite diagnosis. In Italy, individuals wishing to undertake sporting activities at any level undergo a battery of tests which, however, have a low sensitivity and specificity for identifying structural cardiac diseases.15 Hence a large number of unapparent cardiac defects including BAV may go undetected in athletes. Transthoracic echocardiography (TTE) can detect the presence of BAV, but is not performed routinely.16

SUBJECTS AND METHODS

From 1 January 2000 to 31 December 2004, we performed PPS on 2273 competitive athletes (788 females and 1485 males) aged 8–60 years old (mean age 31 (SD 11.3) years) (table 1).

Table 1 Sports practised

The subjects trained for at least two hours at 80% of Vo2max three times a week for at least nine months per year, except for the athletes aged 8–10 years, who trained twice a week for at least nine months per year.

All the athletes underwent the same clinical evaluation, standard 12-lead ECG, exercise test to exhaustion on a treadmill or a cycloergometer, and echocardiography. The treadmill test was performed following the Bruce protocol with a 25-watt progressive increment every three minutes.

Echocardiography

All echocardiographic studies were performed by four experienced board-certified ultrasonographer cardiologists using a Hewlett-Packard Sonos 5500 equipped with 2.5 MHz The ultrasonographer cardiologists routinely worked together, although no formal intra- and inter-tester studies were performed. The main measurements were obtained in the parasternal long-axis view;17 left ventricular mass and left ventricular hypertrophy were calculated from the equation reported by Devereux et al.18

The diagnosis of bicuspid aortic valve was based on the clear demonstration of two cups and two commissures in systole and diastole in the short-axis view. Aortic root dimensions were assessed at end diastole in the parasternal long-axis view at four levels: (1) aortic annulus (AO an, hinge points of the aortic cusps); (2) Valsalva’s sinuses (AO sv); (3) sinotubular junction (STJ); and (4) proximal ascending aorta (PAA), measured 1 cm from the STJ. All the athletes with BAV were assessed together with a group of athletes with a normal tricuspid aortic valve (TAV), matched with the BAV athletes group for age, body surface area (BSA), sport and training.

The presence of aortic regurgitation was evaluated by colour Doppler both in the parasternal long-axis and short-axis views, and in the apical three-chamber and five-chamber views by using the colour-flow mapping method, according to the ACC/AHA 2006 guidelines11 on a scale of 0–4+. The presence of aortic stenosis was evaluated from the apical five-chamber view with continuous wave Doppler. Aortic stenosis was diagnosed when aortic peak velocity was >2.5 m/s (corresponding to a maximum gradient of 25 mmHg).12

The echocardiography examination also included evaluation of all additional anatomic or haemodynamic abnormalities, such as mitral and tricuspid valve regurgitation and pulmonary pressure.

Evaluation of aortic dilatation in athletes with BAV

In cases of BAV, aortic root dilatation at Valsalva’s sinuses and sinotubular junctions was evaluated by comparing the actually-measured dimensions with predicted values calculated according to the regression formula of Roman et al, based on age and body surface area (95% normal confidence limits).

Aortic dilatation was considered pathological when the dimensions actually measured exceeded the predicted ones. Moreover, athletes with BAV were divided into two groups, namely younger athletes (<25 years; n = 20) and adult athletes (>25 years; n = 38).

The aortic dimensions at all measured levels were compared with those of TAV-matched athletes. Upper limits of aortic dimensions were considered to be the mean + 2SD of the values found in TAV athletes, at each level.

Statistics

Descriptive statistics were calculated, and expressed as mean (SD). Differences in mean values between BAV and TAV athletes at each aortic level were analysed using the Student paired t test. A two-tailed probability value of <0.05 was considered to be statistically significant. The association of aortic size at all levels with the degree of aortic regurgitation and years of training was assessed in BAV athletes by calculating Spearman coefficient, at a significance level of p<0.05. Linear regression analysis (Pearson coefficient) was performed to assess the association between aortic root dimension at Valsalva’s sinuses and age, BSA, and years of training, at a significance level of 0.05.

RESULTS

BAV clinical findings

All the athletes with BAV were clinically asymptomatic and the anamnesis was negative. For the objective examination an ejection click and a systolic murmur at the base were heard in 11 and eight athletes, respectively. A diastolic, high-frequency murmur was heard in seven athletes, but in four of them it was only made audible by handgrip. The other athletes had non-specific findings, or had a completely normal physical examination.

Echocardiographic findings of structural heart disease

Of all the athletes studied, (2273), only 1917 had completely normal echocardiographic parameters, while 356 presented structural heart disease (table 2).

Table 2 Abnormal echocardiographic findings (n = 356 of 2273 athletes examined)

In the 71 mild LVH found, no echocardiographic evidence of pathological hypertrophy was detected.

In these cases no overlap of BAV with other cardiac abnormalities and no myocardial chamber enlargement were present. All the cardiac malformations were diagnosed or suspected through transthoracic echocardiography following the parameters expressed in the AHA guidelines.

BAV was identified in 58 athletes (56 males and 2 females; mean age 26.6 (SD 9.1), range 10–45 years), giving a prevalence of 2.5%. In three of these 58 athletes, the definitive diagnosis was made with transoesophageal echocardiography. At the time of diagnosis, these athletes had been training regularly for 10 months a year for 2–5 years.

None of the patients with BAV had any family history of premature sudden cardiac death or familial cardiovascular disease. Only one athlete reported having a brother with BAV. Two male athletes (aged 45 and 41, respectively) had mild hypertension (145–90 mmHg). All the other athletes were normotensive. The EF values were within the normal range (58 (5)%) in the BAV and TAV groups.

ECG findings in athletes with BAV

Minor alterations were found in 22 athletes and major ECG alterations, arousing suspicion of heart disease, were found in two.15 The major alterations consisted of a striking increase in R or S wave voltage (⩾35 mm) in any lead Q waves ⩾4 mm in depth and present in >2 leads; the minor R or S wave voltage (<35 mm) and Q waves <3 mm in depth and present in >2 leads.

Exercise testing findings

All the athletes were submitted to the Bruce treadmill test at up to 80% of maximal effort. No major arrhythmic events, such as ventricular arrhythmias, were observed at rest, or during the test and recovery. However, 732 athletes showed supraventricular and ventricular extrasystolic beats during the test, and 430 athletes during recovery. Of the BAV athletes, only three had similar minor arrhythmic events. All showed a normal increase in heart rate and blood pressure, suggesting a normal cardiac performance.

Valvular functioning

BAV was functioning normally in nine athletes, who showed absence of regurgitant jet in both colour and continuous wave Doppler examinations, associated with normal transaortic flow velocity. Aortic regurgitation was detected in the other 49 athletes, although with widely varying degrees of aortic valvular disease (table 3).

Table 3 Aortic valvular functioning in bicuspid aortic value (BAV)

One of the two athletes with aortic stenosis was a 15-year-old male with a transaortic peak flow velocity of 3.2 m/s, corresponding to a maximum gradient of 40.96 mmHg. The other was a 13-year-old male with a transaortic peak flow velocity of 3.14 m/s, corresponding to a maximum gradient of 40 mmHg. In both these athletes, aortic stenosis was associated with moderate (2+) aortic regurgitation.

Echocardiographic dimensions of aortic root and proximal ascending aorta

In BAV athletes, the prevalence of aortic dilatation, evaluated on the basis of the predicted values, was 81.5% at Valsalva’s sinuses and 86.8% at STJ in the group aged over 25 years; 80% at Valsalva’s sinuses, and 90% at STJ in the group aged under 25 years.

In both these subgroups, aortic root dimensions at all the measured levels were significantly larger in BAV than in TAV athletes (table 4).

Table 4 General characteristics and aortic dimensions in bicuspid aortic valve (BAV) and tricuspid aortic valve (TAV) athletes >25 years and <25 years

In the BAV athletes aged >25 years, the prevalence of aortic dilatation was 31.5% at the annulus (12 of the 38 athletes exceeded the value corresponding to the mean (±2SD of TAV controls), 31.5% (12 athletes) at Valsalva’s sinuses, 34.2% (13 athletes) at the sinotubular junction, and 39.4% (15 athletes) at the proximal ascending aorta. In the BAV athletes aged <25 years, the prevalence of aortic root dilatation was 30% at the annulus (6 of the 20 athletes exceeded the value corresponding to the mean (±2SD) TAV controls), 20% (4 athletes) at Valsalva’s sinuses, 40% (8 athletes) at the sinotubular junction, and 25% (5 athletes) at the proximal ascending aorta.

There was no evidence in either of the BAV subgroups of an association between aortic size at any of the measured levels and the extent of aortic regurgitation. Again, no correlation was found between aortic dimensions and years of training (r = 0.28 at Valsalva’s sinuses, and r = 0.17 at proximal ascending aorta, both NS; table 5)

Table 5 Correlation between aortic size and extent of aortic regurgitation (AR) in the <25 and >25 year group

Athletes who were not allowed to continue competitive sports

Of the 58 athletes with BAV, 15 (all males, mean age 24 (7.8) years; range 13–38 years) were not allowed to continue competitive sports. Four of them had aortic root dimensions at the measured levels within the normal values compared with matched TAV athletes, and they were disqualified because of the presence of moderate-to-severe aortic regurgitation (3+ on colour flow mapping) and left ventricular dilatation (LVIDd >55 mm). One of these athletes, a 13-year-old male, had a stenotic regurgitant valve, with a maximum gradient of 40 mmHg (see above).

In the other athletes who were not allowed to continue competitive sports, aortic dilatation was found. It was moderate (40–45 mm at 1 or more level) in eight of them and severe (>45–48 mm) in the rest. Aortic dilatation was associated with varying degrees of valvular dysfunction: three athletes had mild aortic regurgitation (1+), three moderate regurgitation (2+) and six moderate-to-severe aortic regurgitation (3+). One of them, a 15-year-old male, had a stenotic-regurgitate valve, with a maximum gradient of 40.96 mmHg (see above).

At the time of diagnosis, these athletes had been regularly training for an average of 14.64 years (range 7–23 years), in various sports, including soccer (9 athletes), cycling (1), tennis (4), basketball (1). Also, 13 of them had in the past been allowed to practise competitive sports in primary care sports medicine centres, having been considered free of cardiac disease as evaluated with the standard screening protocol. The other two (one 13-year-old and one 14-year-old male) were young competitive athletes referred to our institution for the evaluation of auscultatory findings, arousing the suspicion of aortic valve disease. In both of them, an ejection click and systolic and diastolic heart murmurs were clearly audible.

DISCUSSION AND CONCLUSIONS

BAV is a congenital condition, seen both in the general population and in elite athletes, with marked preponderance in males.1 2 Few data are available about its incidence in athletes, particularly in competitive non-elite ones. Recently, echocardiography has been used to detect the prevalence of BAV in newborns.13 14 The interest in detecting BAV in athletes arises from the progressive increase in the population of subjects regularly practising sport at a competitive level (non-elite athletes). This model is well defined by Maron.27 Currently in Italy the protocol study for eligibility does not include an echocardiographic examination, even at the beginning of the sport activity, which neglects the importance of several other minor congenital diseases. The ability of physical examination alone to detect BAV is low, particularly in young people, given the inconstant systolic click and the difficulty of recognising the low frequency diastolic murmur associated with aortic regurgitation.20 Indeed, only a few of our subjects had definite findings at the clinical examination pointing towards BAV, and only nine of 58 subjects with BAV showed normal valve function.

The Doppler flow pattern in BAV was valvular insufficiency of varying degrees, supporting the evidence that aortic insufficiency is the predominant haemodynamic lesion of BAV,6 8 more common than stenosis. Similar conclusions were reached by Nistri et al during military screening with echocardiography.21 Our study sample had a high prevalence of relatively young athletes (1712/2273; 75%), and the average age of the athletes with BAV was below 30 years. In fact, with BAV thickening and calcification of the cups occurring in the fourth decade, this increases the importance of an echocardiographic follow-up of the impact of training. We noted that the predominant Doppler pattern in BAV is aortic regurgitation, although we know that 75% of cases commonly show aortic stenosis and over 50% have clinically-significant symptoms after age 40.28 This reflects the propensity for premature fibrosis, stiffening and calcium deposition in the presence of abnormal valve function, and this calcification should be considered when interpreting the low number of young patients in our study with aortic valve. Our results confirm that athletes with BAV had overall significantly larger aortic dimensions compared with TAV controls, and no correlation with the presence and extent of aortic regurgitation and with the aortic size of the other levels was found. In the BAV athletes whose heart performance was similar to that of TAV athletes, aortic dimensions varied widely and were represented homogeneously in the various sports, although in endurance-trained subjects they are physiologically greater than in athletes with similar age and BSA.2225 However no further information about the pathogenesis of aortic dilatation in BAV or aorta dimension in a TAV non-athletic population can be extracted from the results.

What is already known on this topic

  • Bicuspid aortic valve is a common congenital cardiac condition.

  • It is often associated with other vessel abnormalities and anomalies of the left ventricular outflow tract.

  • Athletes with bicuspid aortic valve (BAV) were clinically asymptomatic and the anamnesis negative.

  • The presence of BAV in non-elite athletes has been poorly investigated.

What this study adds

  • Bicuspid aortic valve (BAV) in non-elite athletes has the same prevalence as in the general population (2.5%).

  • The Doppler flow pattern in BAV is predominantly valvular insufficiency, supporting the evidence that aortic insufficiency is more common than stenosis.

  • Echocardiography can easily be used in athletes starting sport activity to detect and follow cardiac congenital disease.

Our study is cross-sectional, and therefore data on the prevalence of BAV, and particularly on its evolution and the impact of exercise on it, are not available. Our data also show that several other major or minor structural cardiac abnormalities may be found in athletes, and indicate that echocardiography can easily be used to study and follow a variety of exercise-induced cardiac responses and modifications. In conclusion, we propose that a short echocardiographic examination should be performed at least once during an athlete’s sporting life. It might be seen as a useful test in the context of PPS for ascertaining the presence of common congenital cardiac conditions in competitive athletes.

Acknowledgments

The authors thank Susan Charlton for her revision of the English manuscript. This paper was accepted as an abstract in the ACC meeting (USA 2004) and Euroecho meeting (Athens 2005).

REFERENCES

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Footnotes

  • Competing interests: None declared.

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